wait, what? is it coarsest common fining or finest common coarsening that we're interested in here?

And isn't common knowledge the set of questions that not only they can both answer, but that they both know that both can answer, and both know that both know, etc etc etc?

Actually, maybe I need to reread this a bit more, but now am more confused.

Actually, on rereading, I think I'm starting to get the idea about meet and common knowledge (given that before exchanging info, they do know each other's partitioning, but not which particular partition the other has observed to be the current one).

Thanks!